The present invention is directed to the subject matter of reinforcing multiple walls usually in a building structure in which a tie is employed to secure two adjacent walls which are parting or otherwise need a tieing arrangement.
Often times structures with multiple wythes brick, stone, concrete block, or even timbers are separated partly due to wind loads. The wind loads can be applied in suction or compression. Finally, extra structure loading may be applied in the form of earthquakes, earth shifts, mud slides, and others.
Various techniques have been developed, primarily in the United Kingdom, for a method of inserting and chemically bonding stainless steel helical ties into wood and masonry to enable the repair stabilization of multiple wythe walls normally having cavities between the wythes. Cavities between the adjacent wythes can be very small. Sometimes even zero in a solid wall, which nonetheless requires reinforcing.
In a proper cavity wall, the cavity will usually be one inch or more. Sometimes in the United Kingdom such cavities will be as wide as 5 inches, but normally in the 2 to 4 inch range. In the United States the gap is commonly approximately 1 inch. One such technique is marketed under the trademark RetroTie(copyright). Normally the tie is inserted from the outside wall, and the tie is driven into the inner wall where the tie itself cuts a thread in the substrate due to its rotation while being hammered into the wall. With harder materials such as brick and concrete, a pilot hole is normally drilled from the outside prior to insertion. The drills used for the pilot holes are normally 4.5 mm diameter drills irrespective of whether the tie is 6 or 8 mm in diameter. With certain softer materials such as soft wood, lightweight concrete, and more unusual materials, such as clay, no pilot hole is needed for that thickness.
The tie may be loaded into the insertion tool and a certain length left projecting for concluding the insertion. This length is determined by the needs of the job. Generally softer material requires deeper penetration. When the tie is inserted the amount of tie protruding is driven fully into the inner wythe, that is, the end of the support tool touches the inner wythe. After driving the tie to the required depth in the inner wythe, the outer end is lying in a clearance hole, which is 10 mm for a 6 mm tie, or 12 mm for an 8 mm tie. A plastic sleeve is pushed over the tie and positioned adjacent to the cavity and thereafter bonding takes place by inserting in the outer wythe a bonding agent such as a polyester or epoxy resin. Exemplary of the foregoing are European Patents Nos. 0150906 and 0171250BT.
An alternative to this technique employs reinforcement bars or threaded bars which are chemically bonded into both the inner and the outer wythes. Also, ties are inserted which may use expansion anchoring techniques or anchoring techniques to fix both ends or with expansion at one end and a chemical at the other. Either one or both wythes have the chemical bonding applied.
The anchoring system as described is comparatively expensive, often times too stiff to permit differential movement between the wythes which occurs during the natural expansion of inner and outer wythe due to temperature and moisture variations. On the other hand, ties sold pursuant to the trademark Helifix(copyright) described hereinafter have both axial load carrying characteristics and offer lateral flexibility. Moreover, they have a built-in ability to shed water that might attempt to migrate from the outer wythe to the inner wythe.
The patent literature relating to the prior art is found primarily in Class 144, subclass 353, exemplary of which is Canadian Patent No. 457,923 and U.S. Pat. No. 3,144,892. Additional prior patents are German Patent No. 935,023, Netherlands Patent No. 8,903,120, WO 87/01,153, British Patent No. 2,237,319, British Patent No. 12,178,099, British Patent No. 2,250,311, British Patent No. 2,141,773, British Patent No. 2,223,556, and German Patent No. 3,716,808.
Of the above, the Canadian Patent is pertinent in that it shows joining two pieces of timber in a splice. The same is done by a dowel having threads which form an angle of 45xc2x0 or more to a vertical plane passing through the dowel. The Canadian Patent fails to teach anything with regard to securing brick to brick. Indeed, it should be noted that each of the five independent Canadian claims represents a xe2x80x9cwooden structural unitxe2x80x9d or xe2x80x9cprefabricated wooden constructionxe2x80x9d to the exclusion of any other type of material. Thus, it is inapplicable to the use of a tie which is in essence a twisted flattened section with a central core and driven through two parallel wythes either brick to brick, mortar to brick, brick to wooden frame, and the like. In U.S. Pat. No. 3,144,892 to Webster, just like the Canadian Patent, each of the independent claims, six in number, refer to a method of fabricating panels, each panel being referenced as xe2x80x9cwood panel componentsxe2x80x9d. Thus Webster, like the Canadian Patent, fails to even address securing adjacent wythes of brick or other building components to each other in reinforcing engagement in an existing building.
The invention finds significant utility in a cavity wall which is usually made with a hollow concrete block as the inner wythe and brick as the outer wythe. The cavity is usually xc2xd to 1 inch and up to 2 inches between the two. The gap may vary from 2 inches to 5 inches or more. The system utilizes a spiral tie which is approximately 7-8 inches or longer. Sometimes the length can be as long as 11 inches, but may be longer or shorter depending upon the materials and the job site. With a 5 to 6 mm pilot hole drilled to the accuracy which can be normally achieved in a brick, the end of the tie will enter the pilot hole quite easily and cleanly. In the two step tie, the diameter is 6 mm and 8 mm, respectively, but may increase or decrease depending upon the application and materials. A special purpose insertion tool is fitted to a standard hammer tool. A center pin is provided in the insertion tool made with an indent to match the pointed end of the tie. The pin is then pressed into the SDS fitting which is the connection into the drill. The tie end is supported by a short sleeve which, when it contacts the face of the wall, retracts against a spring until the tie driving is completed. Usually the pin hammers out a short annular recess below the outer surface of the wall. A modified embodiment of the adapter recognizes that the drill which activates the hammer invariably rotates clockwise. Accordingly, if the spring is wound clockwise, the bottom tail end will dig into its seat. On the other hand, if it is wound counterclockwise, it rotates in a xe2x80x9ctail skidxe2x80x9d relationship to the seat. During the course of insertion, the pull-out resistance of the tie can be checked by using a pull unit. Normally the pull-out load requires determination one wythe at a time. This is achieved by drilling a clearance hole in the first wythe to measure the load achieved from the second wythe by inserting the tie into one wythe only.
In view of the foregoing, it is a principal object of the present invention to provide a method and apparatus for tieing wythes together which is highly economical both from a cost standpoint of manufacture, and from the standpoint of the labor involved in achieving the fix, and also importantly by the elimination of the cost and hazards of a bonding chemical.
Yet another object of the present invention is to provide a multiple wythe apparatus tie and method in which the speed of insertion is high, namely one minute per tie, thereby providing a wall with 60 ties to be secured in approximately one hour.
An additional object of the present invention results from leaving a hole in the wall face which is small, thus minimizing the marking of the wall face, and permitting a small amount of material to be inserted over the tie to mask and seal and water proof.
Another additional advantage of the subject apparatus and method is to provide excellent holding power along with significant lateral flexibility to accommodate expansion, contraction, wind loads, and even earth tremors.
Finally, but not conclusively, another advantage of the apparatus and method permits application on a year round basis with an instantaneous fix, and eliminating the need for a chemical bond which requires certain climatic conditions in order to cure for a full fix and has health and safety implications in its use. dr
Further objects and advantages of the present invention will become apparent as the following description of an illustrative embodiment proceeds, taken in conjunction with the accompanying drawings, in which:
FIG. 1 illustrates diagrammatically a double wythe wall in which one of the ties penetrates the mortar between bricks, and the other tie penetrates the brick body itself;
FIG. 2 is a transverse sectional view taken along section line 2xe2x80x942 of FIG. 1 showing the relationship of the tie and the two adjacent walls;
FIG. 3 is taken along section line 3xe2x80x943 of FIG. 1;
FIG. 4 is a front elevation of the exemplary tie utilized in the method;
FIG. 5 is an end view of the tie shown in FIG. 4 and in slightly enlarged scale;
FIG. 6 shows an alternative embodiment tie the pilot end of which is a diameter smaller than the main body portion;
FIG. 7 is an illustrative view of a workman and a hammer drill inserting a tie illustrative of the present invention into a wall having two wythes where the first penetration is mortar and the second penetration is into a solid such as a brick or a concrete block;
FIG. 8 is a partially diagrammatic view of the hammer drill attachment which produces a unique action in the hammering process enhancing the method of inserting the ties;
FIG. 9 is an exploded view of the adapter shown in FIG. 8;
FIG. 10 is an enlarged view of the area shown in phantom lines by circle 10 in FIG. 8 and illustrating the rotational and non-rotational motion of the critical parts while being hammered;
FIGS. 11, 12 and 13 are sequential views of the testing technique which is selectively utilized to determine the holding power of the tie in the inner wythe in which FIG. 11 illustrates the boring of a large hole in the first wythe and a pilot hole in the second wythe; FIG. 12 illustrates the hammering action through a sleeve in which the fix is secured into the second wythe; and FIG. 13 shows the application of a tensionometer secured to the tie to determine the tension required to dislodge the tie from the inner wythe;
FIG. 14 is a view of the modified adapter approximately the same size and section as that shown in FIG. 9 of the original adapter;
FIG. 15 is a view similar to FIG. 10 but also illustrating the modified adapter; and
FIG. 16 is an exploded perspective view of the modifier adapter.